Donald Trump at a campaign event in Milwaukee on Monday.Credit Eric Thayer for The New York Times

Donald J. Trump will pad over his loss in Wisconsin with a large rally on Long Island on Wednesday night, where some 18,000 people have requested tickets and where he will be standing with a number of supporters, organizers said.

“I am so happy that Wisconsin is over,” said Carl Paladino, one of Mr. Trump’s state chairmen and the 2010 Republican nominee for governor. “They already have rigor mortis setting in on Donald Trump. Now, you’re gonna see what’s gonna happen starting tomorrow.”

He added: “He’s not taking any prisoners, all the way from Long Island to Jamestown, N.Y.,” describing the preparations that have gone into the Trump campaign.

The kickoff rally will be Bethpage, where more than 30 of the state’s 62 county chairmen are expected to announce support for Mr. Trump. Some veteran New York political figures have signed in with the campaign, such as the former Representative John Sweeney, who represented a Columbia County district and who lost to Kirsten Gillibrand in 2006. After leaving office, he was arrested on two occasions on drunken-driving charges. Mr. Sweeney, who has frequently talked about his struggles with alcohol and got sober after his second arrest, is expected to be involved in election compliance work for Mr. Trump.

He’s also sought pledge cards from endorsers, just to be safe. “We don’t want to announce that so-and-so is backing us, especially, like, county chairs and elected types, and find out, that was just hearsay, and it’s not really true,” he said.

Mr. Trump’s candidacy is similar to Mr. Paladino’s in some crucial ways: Both are businessmen and political outsiders who ran insurgent candidacies.

Mr. Paladino has been intricately involved in the preparations, scheduling Mr. Trump to land “in every major population center across the state” over the next two weeks before the April 19 primary.

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